Is there any approximate time frame for introducing backups? Will the backups be included in the current plan or as an optional feature for an additional fee?

I'd also be happy if we can have a timeframe. I don't (and won't) mind paying a bit extra for it, as long as it's coming in the - hopefully - near future.

+1 for this feature...

And instead of connecting the snapshots to a particular machine, it would be nice to be able to buy a block of storage and backup any of our machines into it without having to worry about it going away if a specific machine is removed.

Slicehost (where I moved from) binds the snapshots to the machine it was created from, so if you delete the Slice, you lost your backups of it. It would be better to have it independent, then user's could pre-build custom machines, back them up them and have them ready for deployment at any time.

+1 for BACKUP

I know your linode guys are still working on this.
But it would be better if you can offer an estimated date.

I don't think they'll promise an ETA until they are absolutely certain that the product will be bug-free (to the best of their knowledge) by that date. And the only way to be certain about that is to actually have a bug-free product (to the best of their knowledge) in their hands, in which case why not just launch it and start making money.